Multistage evaporative personal cooler

[willib]

i have an idea for a multi stage  evaporative cooler / air conditioner , for personal use , ie not for a room or anything , just to keep you cool while sleeping.

it consists of concentric tubes within tubes , it would stand about two feet high or a little more .

For power it would use only one or two 12V fans ( pc power supply fans)and several low power low flow water pumps .

on the sides of the tubes would be a wicking material, and the pumps would circulate water from the bottom to top , in each stage.

the idea is , as the air flows twards the center tube it gets progressivly cooler ,also cooling the water in each stage ,so by the time it gets to the center the air will have very little moisture left in it , that is the idea anyway.this air could be used to cool you down while sleeping .the water at the center tube could be circulated through an recycled air conditioner evaporator cooling fin setup. with another fan blowing the cool air past the fins .

i just tested the cooling effect with a wet towel wrapped around a thermometer .

it is 32C , 88F in here ATM

and with the towel and thermometer it got down to 77F , 25C , with this air  flowing into the above aparatus next stage , would it get colder still?

[willib]

this is the airflow diagram

http://www.otherpower.com/images/scimages/2965/air_flow.JPG

[zap]

I would think it would get colder but not much. An appropriate 2 stage evaporative cooler can lower the air temp to lower than wetbulb. Wetbulb is basically what you were measuring when you measured the 77F temp.

About 9-10 years ago I had some friends with an HVAC company show me a 2 stage set up. The temp coming out of the unit was very impressive to say the least. It used 2 fans, one blowing a mist up through a simple metal heat exchanger, much like a tiny cooling tower you'd see for cooling a big building, which cooled the incoming air that fed the main evaporative cooler.

The only problem I see with your "towel setup" is that the air you would be feeding into the second stage already has quite a bit of humidity added to it.

[willib]

Thanks that is the kind of info i was looking for.

i will look up " wet bulb " on the net

Isnt that used to calculate the Relative Humidity?

as long as it is able to get colder than wet bulb , i should be ok , because there will be several stages to this , and if each one gets a little colder then the air comming out at the end should be drier as well.